The correct answer is "subduction zone."
Most of the pulling force driving plate motion is produced at the subduction zone.
In Geology terms, the subduction zone is the part of big collisions of tectonic plates on planet Earth. These plates are large pieces of crust that move very slow -we are talking millions of years- and they move across the surface.
So in this subduction zone, the plates move and collide. One plate bends and slides under the other plate, creating the collision. This collision is so hard that is what causes earthquakes. One example is the volcanic zone called the Ring of Fire.
